ASVAB Mechanical Comprehension Practice Test 177915 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.20
Score	0%	64%

Review

1 If the handles of a wheelbarrow are 1.0 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 200 lbs. load concentrated at a point 1.0 ft. from the axle?

52% Answer Correctly

	203
	200
	0
	-48

Solution

This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: F_ed_e = F_rd_r. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{200 \times 1.0}{1.0} \)
\( F_e = \frac{200.0}{1.0} \)
\( F_e = 200 \)

What type of load creates different stresses at different locations on a structure?

60% Answer Correctly

	static uniformly distributed load
	impact load
	non-uniformly distributed load
	dynamic load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

A block and tackle with four pulleys would have a mechanical advantage of:

79% Answer Correctly

	4
	2
	1
	0

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

Friction between two or more solid objects that are not moving relative to each other is called:

73% Answer Correctly

	static friction
	gravitational friction
	dynamic friction
	kinetic friction

Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?

54% Answer Correctly

	decrease torque
	increase applied force
	increase torque
	decrease applied force

Solution

Torque measures force applied during rotation: τ = rF. Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).